circadian clock is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2025-11-04. Where a claim depends on a specific study, the study is described rather than over-claimed.
Laboratory samples of SR9009 are typically handled as research chemicals rather than pharmaceuticals. Suppliers usually state that the material is for research use only and not for human or veterinary administration. Storage recommendations generally call for a freezer at approximately −20 °C, protection from light, and a desiccated environment. The solid is often described as a white to off-white powder. Solubility is commonly reported in organic solvents such as dimethyl sulfoxide and ethanol, with low solubility in water.
Analytical identification and purity assessment often use high-performance liquid chromatography with ultraviolet detection or mass spectrometry. Liquid chromatography–tandem mass spectrometry is used to detect and quantify SR9009 in biological matrices, including urine and blood, for anti-doping or pharmacokinetic studies. Nuclear magnetic resonance spectroscopy can confirm molecular structure. Stability depends on form and storage: the solid is generally more stable than solutions, and repeated freeze–thaw cycles may degrade samples. Purity is typically reported as a percentage from a certificate of analysis.
SR9009 is a synthetic small molecule studied as an agonist of REV-ERB nuclear receptors. REV-ERB alpha and REV-ERB beta help regulate circadian rhythms and metabolic gene expression. In laboratory research, SR9009 has been used to probe how these receptors affect skeletal muscle, liver, and adipose tissue. The compound was identified in academic drug-discovery work and is often described in scientific literature by its chemical name and research code. It is not an approved medicine, and human clinical data remain limited or absent.
SR9009 binds REV-ERB receptors and alters their repressive activity on target genes. This action can change transcription of genes involved in lipid handling, glucose metabolism, and mitochondrial function. In rodent studies, treated animals have shown changes in muscle oxidative capacity and exercise performance, though effects vary by dose, duration, and model. The precise molecular steps connecting receptor binding to whole-body outcomes are still an active area of investigation. Findings in animals do not automatically translate to humans.
Because REV-ERB receptors are core clock components, SR9009 has been examined for effects on daily rhythms as well as metabolism. Research has explored whether the compound can shift or reinforce circadian gene expression in tissues such as liver and muscle. Some studies report improved metabolic markers in obese or diabetic mice, while others show context-dependent responses. Questions remain about which effects are direct, which are secondary to timing, and how they might differ across species.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Common supplier description |
| Solubility | Soluble in DMSO and ethanol | Low solubility in water |
| Typical storage | −20 °C, desiccated, dark | For research samples |
| Analytical method | LC-MS/MS | Used for detection and quantification |
| Regulatory status | Prohibited in sport | WADA metabolic modulator class |
SR9009 is a synthetic small molecule studied as an agonist of the nuclear receptors REV-ERBα and REV-ERBβ. It is not a steroid, peptide, or natural hormone. In scientific literature, it appears under the code SR9009 and in non-scientific contexts as Stenabolic. The compound was identified through chemical screening efforts aimed at targeting circadian clock components. Its status remains investigational, and no regulatory agency has approved it as a human medicine.
REV-ERB proteins help regulate daily cycles in gene expression, including genes tied to lipid and glucose metabolism. SR9009 binds these receptors and alters their activity in cell and animal experiments. Consequences observed in rodents include changes in skeletal muscle oxidative capacity, blood lipid levels, and exercise performance. The precise chain from receptor occupancy to whole-body effects is still an active area of study. Human responses cannot be assumed from rodent data.
SR9009 is a synthetic small molecule studied as an agonist of the nuclear receptors REV-ERBα and REV-ERBβ. It is not an approved medicine and has no established human therapeutic use. The compound appears in scientific literature as a tool for probing circadian and metabolic regulation. Online sellers often label it as a research chemical, sometimes using the nickname Stenabolic. Its chemical identity is distinct from selective androgen receptor modulators, stimulants, and peroxisome proliferator-activated receptor delta agonists. Researchers use it mainly in cell and animal experiments.
At the molecular level, SR9009 binds REV-ERBα and REV-ERBβ and alters their repressive activity on target genes. These nuclear receptors help regulate the circadian clock, lipid synthesis, glucose metabolism, and inflammatory pathways. By changing transcription, the compound can shift the timing or magnitude of downstream metabolic processes in model systems. It does not act through androgen receptors or adenosine receptors, which distinguishes it from several substances sold for athletic performance. Whether the same transcriptional changes occur in humans at tolerable exposures remains an open question because controlled human studies are lacking.
SR9009 is a synthetic small molecule studied as an agonist of the nuclear receptors REV-ERBα and REV-ERBβ. These receptors help regulate circadian rhythms, lipid metabolism, and inflammatory gene expression. In cell and animal experiments, SR9009 alters transcription of clock-controlled genes and metabolic pathways. The compound is not a hormone and does not resemble classical steroid structures. Its activity depends on binding to the ligand-binding domain of REV-ERB, where it can modify corepressor recruitment.
Research interest in SR9009 grew from studies of circadian biology and metabolic disease. Preclinical reports describe effects on exercise capacity, muscle metabolism, and blood lipid levels in rodents, but these findings come from controlled laboratory settings. The compound has low oral bioavailability in animals, which limits systemic exposure after swallowing. Investigators often use injected routes in experiments to achieve measurable plasma concentrations. Human clinical data are sparse, no approved therapeutic product exists, and whether animal effects translate to humans remains an open question.
SR9009 is a synthetic small molecule studied as an agonist of the nuclear receptors REV-ERBα and REV-ERBβ. These receptors help regulate circadian rhythms and metabolic gene expression. In laboratory experiments, SR9009 binds these receptors and alters transcription of genes involved in lipid handling, glucose metabolism, and mitochondrial function. It is not a naturally occurring compound and has no approved therapeutic use. Research interest stems from its ability to modify energy metabolism in cells and animal models.
In rodent studies, SR9009 has been reported to increase mitochondrial content in skeletal muscle and improve exercise endurance under some conditions. These findings led to popular descriptions such as an exercise mimetic, although that term oversimplifies the biology. Effects vary by dose, timing, tissue, and model. The compound's influence on circadian pathways means that time of administration can matter in experiments. Whether similar metabolic changes occur in humans remains largely unexplored in controlled published trials.
== Interactions == Previously, doxycycline was believed to impair the effectiveness of many types of hormonal contraception due to induction of CYP450 enzymes (a family of liver enzymes that break down drugs, potentially accelerating the metabolism of hormonal contraceptives). Research has shown no significant loss of effectiveness in oral contraceptives while using most tetracycline antibiotics (including doxycycline), although many physicians still recommend the use of barrier contraception for people taking the drug to prevent unwanted pregnancy.
=== Blood test === see also: blood doping The blood test detects illegal performance enhancement drugs through the measurement of indicators that change with the use of recombinant human erythropoietin:
From September 23 to 25, 2026, Xi Jinping, the general secretary of the Chinese Communist Party and president of China, and his wife Peng Liyuan made a state visit to the United States, hosted by President Donald Trump and First Lady Melania Trump. It reciprocated Trump's state visit to China in May 2026. It was Xi's second state visit to the US; his first occurred in September 2015. It was also his sixth US visit since he assumed power in 2012. Trump personally greeted Xi at Joint Base Andrews, the first time a US president personally greeted a foreign leader except the Pope at the base since 1962, and a ceremony was held there. During the visit, Xi was received by Trump at the White House, where the two leaders held talks at the Oval Office and went to the White House Rose Garden for a military troop review. Later, Trump hosted Xi for a state dinner. The next day, the two leaders held a tea ceremony at the White House. Afterwards, the two leaders visited the National Archives of the United States, where they viewed the founding documents of the US. Xi and Peng concluded the trip and returned to China. The visit will be followed by Trump's visit to Shenzhen for APEC China 2026 and Xi's visit to the United States for the 2026 G20 Miami summit.
Sources: en.wikipedia.org
== Artificial cartilage == Synthetic cartilage can be composed of many different materials that mimic its functional properties. Tissue engineering principles include the use of cells, growth factors, and synthetic scaffolds in order to do this.
== Variants == A common variant is Lillie's trichrome, which uses aniline blue instead of a green dye. It is often erroneously called Masson's trichrome. It differs in the dyes used, their concentrations, and the immersion times. Another common variant is the Masson trichrome & Verhoeff stain, which combines the Masson trichrome stain and Verhoeff's stain. This combination is useful for the examination of blood vessels; the Verhoeff stain highlights elastin (black) and allows one to easily differentiate small arteries (which typically have at least two elastic laminae) and veins (which have one elastic lamina).
This test can be used to measure the aggregate modulus of cartilage, which is typically in the range of 0.5 to 0.9 MPa for articular cartilage, and the Young's Modulus, which is typically 0.45 to 0.80 MPa. The aggregate modulus is "a measure of the stiffness of the tissue at equilibrium when all fluid flow has ceased", and Young's modulus is a measure of how much a material strains (changes length) under a given stress. The confined compression test can also be used to measure permeability, which is defined as the resistance to fluid flow through a material. Higher permeability allows for fluid to flow out of a material's matrix more rapidly, while lower permeability leads to an initial rapid fluid flow and a slow decrease to equilibrium. Typically, the permeability of articular cartilage is in the range of 10^-15 to 10^-16 m^4/Ns. However, permeability is sensitive to loading conditions and testing location. For example, permeability varies throughout articular cartilage and tends to be highest near the joint surface and lowest near the bone (or "deep zone"). Permeability also decreases under increased loading of the tissue. Indentation testing is an additional type of test commonly used to characterize cartilage. Indentation testing involves using an indentor (usually <0.8 mm) to measure the displacement of the tissue under constant load. Similar to confined compression testing, it may take hours to reach equilibrium displacement. This method of testing can be used to measure the aggregate modulus, Poisson's ratio, and permeability of the tissue.
Sources: en.wikipedia.org
Legality depends on the country and the intended use. In many places it is sold as a research chemical, but sports and medicine regulations restrict it.
Detection commonly uses liquid chromatography–tandem mass spectrometry. This method can identify the compound in urine or blood at low concentrations.
Typical guidance is −20 °C, dry, and protected from light. Solutions should be aliquoted and limited freeze–thaw cycles should be used.
SR9009 is a synthetic research compound that acts on REV-ERB nuclear receptors. It is not approved for human use and is sold only as a research chemical. Its effects have been studied mainly in cells and rodents.